


Bioluminescence

by SesuRescue (Kigachan)



Category: Undertale (Video Game)
Genre: Anxiety, Bad Puns, Bioluminescence, Fluff, Incest, Multi, Sibling Incest
Language: English
Status: Completed
Published: 2018-08-13
Updated: 2018-08-13
Packaged: 2019-06-27 02:12:59
Rating: General Audiences
Warnings: No Archive Warnings Apply
Chapters: 1
Words: 1,063
Publisher: archiveofourown.org
Story URL: https://archiveofourown.org/works/15675945
Author URL: https://archiveofourown.org/users/Kigachan/pseuds/SesuRescue
Summary: The boys take a trip to see a natural phenomenon on the coast. As expected, Grillby isn't exactly thrilled.





	Bioluminescence

**Author's Note:**

> This is being posted a little late, but it was made for a challenge prompt some time ago. We were given a few different images to make a fic from, and I chose an image of bioluminescent waves.

Grillby sighed for the umpteenth time that day, resting his chin on his hand as he looked out the window. “...Why are we doing this again?” **  
**

“BECAUSE IT'LL BE COOL,” Papyrus said, taking care to keep as much eye-contact with Grillby as he could while still focusing on the road. He settled for glancing out of the corner of his socket every few seconds, noting the erratic flickering of flames every few seconds.

“more like it'll be hot,” Sans piped up from the back seat, earning a collective groan from the other two.

“SANS, WHAT DID I TELL YOU ABOUT PUNS IN THE CAR?” Papyrus shook his head in disbelief before addressing Grillby again. “HE IS RIGHT THOUGH, IN A SENSE. THE BEACH SHOULD BE NICE AND WARM WHEN WE GET THERE.”

“...I hate the beach.”

“I KNOW THAT YOU JUST HATE THE WATER GRILLBY, BUT I PROMISE IT’LL BE WORTH IT. ACCORDING TO THE UNDERNET POST I READ, THE WAVES ARE GLOWING!”

“definitely an illuminating experience.”

Papyrus once again ignored Sans, slowly easing down on the brake as they approached the first traffic light they’ve seen in about an hour. He waited until they had stopped before turning in his seat to face Grillby fully. “TRY TO HAVE FUN, FOR ME?”

“...Fine,” Grillby said as he slumped down into the car seat. He felt Papyrus’s eye-lights linger on him for a little longer before the car went into motion again, and he preoccupied himself with looking out of the car window.

The place was interesting, especially since none of them had seen a town on the surface like this before, but Grillby couldn’t fully enjoy it. How could these people live so close to the ocean, and like it?? He just couldn’t comprehend it.

They slowed to a crawl as they approached a ticketed gate and, after grabbing the flimsy strip of paper from the machine, Papyrus parked the car smack dab in the middle of the lot.

“OKAY, WE ARE READY TO GO!” Papyrus cheered, opening his door and stepping out onto the ground. “I’LL GO GRAB THE STUFF FROM THE TRUNK AND MEET YOU GUYS AT THE GATE!”

Grillby nodded but made no effort to move. Maybe if he sat very still, Papyrus wouldn’t notice that he wasn’t there?

Unfortunately, he had forgotten about Sans. “hey, hotstuff, you alright?”

Grillby shrugged. Was he alright?

Physically he was okay. The weather was nice out, gorgeous even considering the late hour. The scenery was beautiful, as long as he didn’t look at the water--oh, there was the anxiety again.

He focused on shooing away the intrusive thoughts in his head, not even noticing that Sans had left until his door had opened. Sans extended a hand in his direction with a smile: a genuine one, not his normal permanent grin. “come on, i won’t let anything bad happen to you.”

“...my hero,” Grillby deadpanned, although on the inside he was relieved. He loved Papyrus to death, but Papyrus had the tendency to get over-excited. Usually, he loved that, but Sans’s mellow aura was exactly what he needed right now. Grabbing the offered hand, Grillby got out of the car and placed a quick smooch on Sans’s skull before righting himself.

The two of them headed over to the gate where Papyrus was bouncing on his feet excitedly. His arms were full of towels and a rather large picnic basket, but from the way he was hopping about the basket looked almost weightless.

Sans nudged Grillby when they were within earshot of Papyrus with a grin. “looks we better hop to it, or Papyrus will be hopping mad.”

“DO YOU WANT TO BE LEFT IN THE CAR?”

Sans paused mid-laugh to stare at Papyrus with wide eye-lights. “you wouldn’t really do that, right?”

“IF YOU KEEP IT UP I’LL HAVE TO STRONGLY CONSIDER IT,” Papyrus said playfully. “NOW, LET’S GO.”

The three of them walked towards the beach, and each step caused Grillby’s flames to flicker the closer they got. Sans must’ve noticed, for he turned to Papyrus and used his free hand to sign something to him. He had been too slow to see the message that had been passed along, but suddenly his vision was obscured by large, skeletal hands.

“...What are you doing?”

“HELPING YOU,” Papyrus replied simply. “WE REALLY WANT YOU TO ENJOY THE VIEW, BUT YOU CAN’T DO THAT IF YOU’RE FRETTING OVER IT.”

Grillby sighed. Papyrus and Sans had really been looking forward to this trip. The least he could do was try it their way. “...Okay.”

He allowed the two of them to slowly guide him, nearly sighing in relief when the solid ground gave way to soft, warm sand.  Papyrus and Sans began to talk loudly to one another as they walked further in, and Grillby realized after a moment that they were doing it to mask the sound of the waves. How were his boyfriends so amazing?

“OKAY, GRILLBY, ARE YOU READY TO SEE THE AMAZING VIEW?!”

Grillby took in a deep breath. “...As ready as I’ll ever be.”

Papyrus removed his hands and Grillby slowly opened his eyes.

The first thing that Grillby registered was just how blue the water was. He was pretty sure that he had never water in such an intense shade of blue before. The color brightened the closer the water came to the shore, and upon further examination he noticed small, glowing blobs dotting the surface. This view, along with the setting sun, it was, it was just--

“...Wow,” Grillby exhaled, much to the delight of the other two.

Papyrus clapped his hands together. “I JUST KNEW YOU’D END UP LOVING IT!”

“...How is this happening?” Grillby asked.

“it’s called bioluminescence,” Sans explained as he took a seat in the sand. Grillby followed him down, not daring to let his eyes leave the sight for a second. “there are millions of tiny organisms out there, and when something disturbs the water they light up like that, causing the phenomenon.”

“...very interesting.”

“ISN’T IT?!” Papyrus wrapped his arms around both Sans and Grillby as he sat down between them. “I FIGURED THAT IT WOULD BE VERY EXCITING TO SEE, AND I WAS RIGHT!”

“you sure were, paps.”

“SO???” Papyrus shifted to look at Grillby. “WHAT DO YOU THINK?”

“...I think that you were right; it is...pretty cool.”

**Author's Note:**

> Thank you as always for reading, I really appreciate it! Check out my NSFW tumblr: [Sesurescue](http://Sesurescue.tumblr.com)


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